Power management in an information channel

Abstract

Methods and associated apparatus to reduce electrical power consumption in an information channel may include identifying times at which to restore power to elements in the information channel, and restoring power to the elements at the identified times. Times for each element are identified based on a recovery time for that element to reach a sufficiently stable operating point before a transition to an active mode of operation. By maximizing the length of time individual elements may stay in the reduced power mode, power savings may be maximized without negatively affecting information channel performance.

1. A method, comprising:
 reducing electrical power being consumed by each of two or more power-consuming elements in an information channel when the information channel is in a first mode of operation; 
 identifying, separately for each element, a time at which power must be restored to that element for that element to reach a sufficiently stable operating point before a transition to a second mode of operation; and 
 restoring power to each element at or approximately at the corresponding identified time. 
 
     
     
       2. The method of  claim 1 , wherein the first mode of operation comprises a power saving mode. 
     
     
       3. The method of  claim 2 , wherein the information channel comprises a read channel in a data storage device. 
     
     
       4. The method of  claim 3 , wherein the second mode of operation comprises a read mode. 
     
     
       5. The method of  claim 4 , further comprising servo wedge information in the information channel during the second mode of operation. 
     
     
       6. The method of  claim 4 , wherein the information channel comprises a pre amplifier. 
     
     
       7. The method of  claim 6 , wherein a first one of the elements comprises a first circuit in the pre-amplifier to process a signal received by the pre-amplifier. 
     
     
       8. The method of  claim 6 , wherein a second one of the elements comprises a second circuit to process signals output by the first circuit. 
     
     
       9. The method of  claim 1 , wherein identifying, for each element, a time at which to restore power comprises identifying, for each element, a predetermined minimum length of time required after power is restored to the element for the element to become sufficiently stable to operate within predetermined performance specifications. 
     
     
       10. The method of  claim 1 , wherein restoring power to each of the elements before each of the corresponding identified times comprises restoring power to each of the elements within a predetermined range of time before the identified time to restore power to each element. 
     
     
       11. The method of  claim 1 , wherein reducing the power being supplied to each of the elements in the channel comprises removing substantially all of the power being supplied to each of the elements. 
     
     
       12. The method of  claim 11 , wherein the predetermined range of time comprises a function of a predetermined number of cycles of a clock signal. 
     
     
       13. The method of  claim 11 , wherein the predetermined range of time comprises a predetermined length of time. 
     
     
       14. The method of  claim 1 , wherein the identified times for each element are different. 
     
     
       15. A method, comprising:
 reducing electrical power being consumed by each of two or more power-consuming elements in an information channel when the information channel is in a power save mode of operation by removing substantially all of the power being supplied to each of the elements; 
 identifying, separately for each element, a time at which power must be restored to that element for that element to reach a sufficiently stable operating point before a transition to an active mode of operation, wherein the identified times for each element are different; and 
 restoring power to each element at or approximately at the corresponding identified time. 
 
     
     
       16. The method of  claim 15 , wherein the active mode of operation comprises a read mode. 
     
     
       17. The method of  claim 15 , wherein at least one element in the information channel comprises an amplifier. 
     
     
       18. The method of  claim 15 , wherein restoring power to each of the elements before each of the corresponding identified times comprises restoring power to each of the elements within a predetermined range of time before each said identified time. 
     
     
       19. The method of  claim 11 , wherein the predetermined range of time comprises a function of a predetermined number of cycles of a clock signal. 
     
     
       20. A computer-readable medium comprising instructions that, when executed by a processor, cause the processor to:
 reduce electrical power being consumed by each of two or more power-consuming elements in an information channel when the information channel is in a first mode of operation; 
 identify, separately for each element, a time at which power must be restored to that element for that element to reach a sufficiently stable operating point before a transition to a second mode of operation; and 
 restore power to each element at or approximately at the corresponding identified time.